Symptoms & Management of CO Poisoning

Symptoms and Management of CO Poisoning

Common SymptomsMaking the DiagnosisTable of Commonly Seen SymptomsA Classification of Carbon Monoxide Poisoning Based on Clinical FeaturesDiagnostic Tests that may be Useful in CO PoisoningWhat to Do About CO Poisoning

Common Symptoms

Making a diagnosis of CO poisoning is crucial, as acute high level CO poisoning can be fatal in just a few minutes. The symptoms are usually multiple, many are non-specific, and some are vague. They can involve many of the body systems. Please be aware that the symptom list below is not complete and that they often do not follow this rank ordering at presentation. Moreover, many of the more severe symptoms (eg. below ataxia) are only seen with acute high level CO exposure.

Symptoms in Order of Increasing Severity of CO Poisoning

Headache

Dizziness on exertion

Fatigue, weakness

Palpatations

Nausea, vomiting

Dyspnea on exertion

Cutaneous vessel dilation

Mental Confusion, difficulty with thinking

Fine manual dexterity abnormal

Tachycardia

Visual disturbances

Hallucinations, confusion>

Ataxia

Retinal hemorrhages

Syncope, collapse

Tachypnea (increased ventilation), further tachycardia

Lactic acidosis

Hypothermia

Cheyne Stokes ventilation

Coma, convulsions

Hypotension

Cardiac and ventilatory depression

Cardiorespiratory failure (death)

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Making the Diagnosis

Making a diagnosis of CO poisoning is crucial, since the condition can be fatal in just a few minutes. The symptoms are widely varied, many are non-specific, and can involve many body systems.

Victims often believe, or are led to believe, that they are have the "flu", gastroenteritis, etc. CO poisoning is very often misdiagnosed clinically as:

Psychiatric illness

Migrane

Stroke

Drunkeness

Heart disease

Food poisoning

There are clues that signal the likelihood of CO poisoning:

If everyone in the family suddenly becomes ill with some of the above symptoms.

If the victim is in a situation where he or she may be exposed to high CO levels.

If symptoms are relieved when the victim moves to a different location / into fresh air.

As a noted emergency room physician has said, "the standard of care for carbon monoxide poisoning may well be misdiagnosis"

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Table of Commonly Seen Symptoms

The following is a list of symptoms which have been applied mainly to acute CO poisoning. Many sources suggest they can be closely related to blood COHb level. Please note that in practice, severity of symptoms DO NOT correlate well with COHb level. Thus, any conclusions about COHb from symptoms, or vice versa, should be drawn with the greatest caution!

0%-5%

No obvious symptoms

5%-10%

Decreased tolerance for exercise in persons with existing pulmonary disease

Decreased angina threshold

Decreased threshold for visual stimuli

10%-20%

Headaches

Dizziness

Confusion

Decreased visual acuity

20%-30%

Severe headache

Nausea

Dizziness

Increased respiration

Irritability

Impaired judgement

Visual disturbance

30%-40%

Vomiting

Decreased awareness

Cardiac irregularities

Muscle weakness

40%-50%

Fainting

50%-60%

Convulsions

Paralysis

60%-70%

Coma

Usually death in a few minutes

70% -and up

Immediately fatal

Lesions Resulting From CO Poisoning

Brain

Acute- Cerebral edema and hemorrhages

Chronic- Necrotic lesions in basal ganglia and demyelination

Heart

Acute- Myocardial necrosis

Chronic- Myocardial infarcts

Lungs

Primary- Pulmonary edema

Secondary- Aspiration pneumonia in comatose patients

Liver

Lobar necrosis with chronic repeated exposure

Kidney

Parenchymatous degeneration leading to necrosis

Muscles

Intramuscular hemorrhages, swelling, and rhabdomyolysis

Bone

Marrow hypertrophy in chronic CO-hypoxia

Skin

Erythema, blisters, and gangrene

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A Classification of Carbon Monoxide Poisoning Based on Clinical Features

Clinical Degree of Intoxication

Symptoms

I - Mild

Headache, vomiting, tachycardia, no disturbances of consciousness

II - Moderate

Disturbances or loss of consciousness without other neurological symptoms, tachycardia, nocioceptive reflexes still intact

Comment: Many many different classifications of severity of CO poisoning are in existence. Just as COHb level does not correlate well with short-term symptomatology or with the longterm effects, the symptoms and effects of CO poisoning do not fit easily into discrete classes as the above suggests. This table is presented as just one possible approach to classification of the effects of CO poisoning, but not necessarily one embraced by the website writer.

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Diagnostic Tests that may be Useful in CO Poisoning

Carboxyhemoglobin Saturation

other Arterial blood gases and pH

Complete blood count

Serum glucose and lactic acid concentration

Serum electrolytes, and urea nitrogen and creatinine concentrations

Urine analysis

Electrocardiogram and echocardiogram

Chest X-ray

Serum creatine kinase (CK) and lactate dehydrogenase (LDH) activities

Serum aspartate and alanine transferase (SGOT, SGPT) activities

Serum myoglobin concentration

Neuropsychologic screening test

Drug screening

Electroencephalogram.

Cerebral computed tomography

Note: With the exception of neuropsychologic evaluation, most of the above tests are usually only of value in acute, higher-level CO poisoning. In such instances, the first eight tests should be done as quickly as possible after presentation.

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What to Do About CO Poisoning

In the early days of mining, caged canaries were hung in the tunnels. The birds, being so small, were especially susceptible to poisonous gases because of their high metabolism and ventilation rate. If the bird died, it was an alarm telling the miners get out of the mine. Now electronic CO detectors are available for the home.

It is best to avoid exposure to sources of CO

Make sure fuel-burning equipment is working correctly and is properly exhausted. This includes furnaces, hot water heaters, and propane and gasoline powered vehicles used indoors.

Stop smoking.

Don't leave your car running in the garage, especially if it is attached to your house. It could poison you in the car, and CO could get into the house and afflict others.

If you are in heavy traffic, keep your windows rolled up. This is especially true if you are caught in traffic in an enclosed space like a tunnel.

Management of CO Poisoning - Quick Points

Remove victim from the site of CO exposure

oxygen immediately - If possible take a blood sample for COHb before this is done

Use endotracheal intubation in comatose patients to facilitate ventilation

Remove the patient to a hyperbaric facility when indicated (if at all possible)